1. Field of the Invention
This invention relates to citric acid, and more specifically to a new chemical process for the production of citric acid which utilizes novel cyclopentene derivatives.
2. Description of the Prior Art
Citric acid, by virtue of its palatability, low toxicity and ease of assimilation, has become one of the most widely used acidulants in the food and pharmaceuticals industries. Both the acid and its salts find use in beverages, jams, jellies and gelatin preparations. Sodium citrate is particularly valuable as a sequestering agent in detergents.
Citric acid is usually produced by fermentation methods, using, for example Aspergillus niger or a yeast of the genus Candida. There are also several chemical methods known for the synthesis of citric acid. Haller and Held, Ann. Chim. Phys., 23 145 (1891), reported a method starting from .beta.-ketoglutaric acid, and Dunschmann, Justus Liebigs Ann. Chem., 261, 162 (1891), described a similar method utilizing diethyl .beta.-ketoglutarate. Fischer and Dangschat, Helv. Chim. Acta, 17, 1196 (1934), obtained citric acid from quinic acid, and Baer et al., J. Amer. Chem. Soc., 61, 2607 (1939), showed that the methyl ester of quinic acid can also be converted into citric acid. Belgian Pat. No. 784,238 discloses a process involving the oxidation of 3-methylene-1,5-pentanediol or several of its chemical equivalents.